1. Field of the Invention
This invention relates to a biological reaction layer and a process for the preparation of the same.
2. Description of Prior Arts
A number of analytical systems for detecting and quantitatively analyzing trace components in a liquid sample, for example, biochemically active components and other organism-originating components contained in a biological fluid such as body fluid, using an analytical element (dry analytical element) constituted in a form of a layer (or sheet) have been well known. The analytical element is generally employed in such a manner that a material chemically or physically reactive to a substance to be analyzed (analyte) upon contact therebetween incorporated previously into the analytical element is brought into contact with the analyte in a liquid sample introduced into the element in an analysis operation to undergo a certain reaction within a biological reaction layer, and the amount of the reaction product or the unreacted substance is measured by spectrophotometry or fluorometry, or by radioisotope to determine the amount of the analyte.
Since the above-mentioned analytical method utilizing an analytical element is relatively simple in the analytical operation, the method has been used for many purposes, for example, in immunoassay utilizing antigen-antibody reaction, analysis of enzyme or substrate utilizing enzymic reaction or the like. However, the so advantageously simple method using analytical element has a drawback such as insufficient analytical sensitivity.
For instance, the above-mentioned drawback is particulary serious in the immunoassay. More in detail, in order to obtain analytical results with high sensitivity, it is required in the immunoassay that a liquid sample of a sufficient volume is introduced in an analytical element within a short time, and then the liquid sample must be retained for a sufficient period of time to complete the antigen-antibody reaction. However, the liquid sample of sufficient volume per unit area is hardly retained in a conventional analytical element, and hence the sufficient sensitivity can not be obtained. A number of analytical elements have been proposed to eliminate such disadvantagous feature in the immunoassay but these elements have eliminated the above-mentioned disadvantage only insufficiently.
Furthermore, the above-mentioned disadvantage is also true to a certain extent in other analytical methods using analytical elements in which enzymic reactions or other various reactions participates.